嘉義縣收購外來種沙氏變色蜥蜴喊停

嘉義縣收購外來種沙氏變色蜥蜴喊停【聯合報╱記者魯永明／即時報導】
2009.07.22 08:37 pm

嘉義縣水上鄉三界埔村遭外來種沙氏變色蜥入侵多年，縣府爭取中央補助，鼓勵村民捕捉，以每隻20元收購，原訂6月到10月，為期5個月，收購2萬多隻，結果不到2個月，捕捉逾3萬多隻，超出目標，農業處被迫22日收購喊停。

有政府收購誘因，三界埔村民與成功國小學童，將捉蜥當成全民運動，休閒又可賺外快，成功國小100多名學童1個多月，共捕捉2000隻，賺4萬多元，村民也紛紛投入捕捉。

截至22日為止，農業處共收購3萬4000多隻，支付逾60萬元，中央補助只有2萬隻、50萬元額度，補助額用完，農業處不得不暫時喊停，再向中央爭取補助。

農業處綠化保育課長曾永華指出，沙氏變色蜥長約4.8到6.4公分，屬中小型變色蜥，環境適應力很強，已知入侵墨西哥、牙買加、貝里斯和美國等地，最大特徵是求偶或示警時，會突起橘紅色喉囊。

沙氏變色蜥曾在花蓮發現，數量不多，不像三界埔地區族群密集，從2000年發現至今，估算數萬隻之多，為避免變色蜥破壞本土物種生態，發布「通緝令」，定點設收集桶，鼓勵村民和學生捕捉。

鄭永華說，沙氏變色蜥肉食性，以蟋蟀、蝗蟲、螞蟻等昆蟲為食，也覓食綠蜥、蜥蜴、攀木蜥蛋，研究發現，有沙氏變色蜥存在，螞蟻數量銳減一半以上，螞蟻具分解落葉等生態功能，螞蟻減少嚴重衝擊地生態，變色蜥在台幾無天敵，又具擴散入侵力，不撲滅任其擴散，恐將釀成生態浩劫。

【2009/07/22 聯合報】

印度高止山脈西北部產東虎屬之一新種

文獻來源: Giri VB, Bauer AM, Gaikwad KS. 2009. A new ground-dwelling species of Cnemaspis Strauch (Squamata: Gekkonidae) from the northern Western Ghats, Maharashtra, India. Zootaxa 2164: 49-60.

Abstract
A new species of gecko of the genus Cnemaspis is described from the forests of the Western Ghats region of Maharashtra. Cnemaspis kolhapurensis sp. nov. is diagnosable by the following combination of characters: dorsal scales homogenous, small and feebly keeled; no spine-like tubercles on flanks, ventrals smooth, imbricate, 20–23 scale rows across venter, between lowest rows of dorsal scales. Supralabial I narrowly contacting nasal. Paired postmentals separated by one or two enlarged gular scales. A continuous series of 24–28 precloacal-femoral pores. The continuous series of precloacal and femoral pores exhibited by this species is unique among Indian members of the genus.

Devario aesculapii - 緬甸西南部產大斑馬之一新種

文獻來源: Kullander SO, Fang F. 2009. Danio aesculapii, a new species of danio from south-western Myanmar
(Teleostei: Cyprinidae). Zootaxa 2164: 41-48. [全文下載]

Abstract
Danio aesculapii, new species, is described from small rivers on the western slope of the Rakhine Yoma in south-western Myanmar. It is superficially similar to D. choprae from northern Myanmar in having a series of vertical bars anteriorly on the side, but differs from it and other species of Danio in having six instead of seven or more branched dorsal-fin rays, and from all other species of Danio except D. erythromicron and D. kerri in having 12 instead of 10 or 14 circumpeduncular scale rows.

Devario xyrops - 緬甸西南部產大斑馬之一新種 (=Devario TW02)

文獻來源: Fang F, Kullander SO. 2009. Devario xyrops, a new species of danionine fish from south-western Myanmar (Teleostei: Cyprinidae). Zootaxa 2164: 33-40. [全文下載]

Abstract
Devario xyrops is described from small rivers on the western slope of the Rakhine Yoma in south-western Myanmar. It is distinguished from all other species in the genus except D. anomalus by its colour pattern including a dark blotch or condensed series of vertical bars anteriorly on the side, separate from a posterior dark horizontal band; and distinguished from D. anomalus in particular by deeper body (29.9–35.8% SL, vs. 25.0–26.8 % SL) and fewer lateral line scales (31–33, modally 32 vs. 33–35, modally 34).

圖片連結: Danios.info

吼~~可以不要再以訛傳訛說食蛇龜會把蛇夾死好嗎? 真的很煩捏

海關查獲外籍船員涉嫌走私大批保育動物 2009-07-21
中國時報 【李翰／高雄報導】

高雄關稅局緝私關員十八日晚上在CHANGHONG輪冷凍倉庫內，查獲意圖走私出口保育類食蛇龜二百卅一隻，涉嫌走私的印尼籍船員SUTRISNOSARJUNI被依違反野生動物保育法移送法辦。

CHANGHONG外籍輪當晚停泊高雄港卅四號碼頭，高雄關稅局緝私人員上船抄船時，在冷凍艙內驚見二百卅一隻藏匿在布袋內的「烏龜」，經送屏科大及內政部警政署森林暨自然保育警察屏東分隊鑑定後，昨天確定為學名Cuora flavomarginata的保育類「食蛇龜」。

船上船員表示，這些烏龜係印尼籍船員SUTRISNOSARJUNI所有，海關依違反野生動物保育法，將他移送港警局偵辦後移送法辦，食蛇龜則交由市府相關單位處理。

食蛇龜主要分布在中國南部、台灣及日本琉球，主要以果實、小動物為食。該龜類可夾住蛇的頭，直到蛇窒息後再把它吃掉，所以才被稱為「食蛇龜」，該龜類在我國屬第二級保育的珍貴淡水陸龜，不能走私買賣。

2009-07-20新進魚隻

Corydoras sp. "New Violet I" 西屯路產新紫羅蘭鼠 x 3

今日主題是那些有尾柄黑斑的鼠魚之間的關係, 倒底紫羅藍鼠(C. similis), 新紫羅藍鼠(C. New Violet I)與C66(= C. "matsuzakae")倒底是不是同一種魚呢? C66被認為是一種長吻的鼠魚, 而New Violet I與similis的差異在於尾柄的黑斑, 前者具有清楚的界限, 而後者則是模糊地擴散到身體中央. 不過有趣的我們目前做出來的結果顯示C66與一般的紫羅藍鼠混在一起, 反倒是不太容易區分的新紫羅藍鼠看比來與similis的遺傳距離比較大一些. 所以這有沒有可能是因為C66的sample量太少的關係呢? 另外從這個關係也可以看出來, 有尾柄黑斑的物種似乎形成一個單系群, 不過紅鱗鼠(C. ourastigma)則與這群物種的關係很遠.

魚隻來源: 澤苑水族 (台中)
圖片連結: rva, a-forest.jp

水族寵物展 - 阿不就是一堆人把狗帶去那裏大便掉毛弄得很臭嗎?

2009年台北水族暨寵物用品展17日至20日在台北世貿三館展出，並以2010年台北國際花卉博覽會為主題。水族寵物展中還有眾多低價優惠、超值好禮讓 民眾撿好康，每日限量100個超值福袋，只要主人和寵物們一起打扮成夏日海攤風即可獲得。[影音] 阿那個記者連稿都念不好是在搞什麼東西啊?

2009-07-18新進魚隻

Corydoras sp. 待查雜鼠 x 7 (金線黃花鼠中挑出) (台族)

Corydoras kanei 佧內豹鼠 x 2 (小黑)
Corydoras crimmeni 克瑞曼鼠 x 2 (小黑) (日名: セミロングノーズカネイ)
Corydoras sp. C53 長吻海盜鼠 x 3 (水世界)
Corydoras "Venezuela Black" 黑鼠 x 11 (企圖繁殖一缸仙草蜜) (石頭)
Pseudohemiodon apithanos 陰陽直升機 (=變色龍直升機) x 7 (水世界)
Hyphessobrycon minor 米諾水晶旗 x 4 (石頭)

今天比較有趣的其實是那個"雜鼠". 根據小黑的店老闆大大表示那個雜鼠是來自阿勇水族的某一批"帕斯塔茲鼠" (C. pastazensis) (不過就一整個不是). 乍看之下非常類似皇冠豹鼠(C. delphax), 但是身上的斑點是如C. kanei的細點, 而背鰭下方不是C. delphax的一整塊黃色區域, 而是一條金線, 背鰭下方也缺乏大的黑色塊, 身上的點不像ambiacus, agassizii這些種類那麼大, 也不像馬鞍鼠ephippifer那麼整齊沿著鱗片邊緣排列, 後來想起來了, 會不會是與kanei共棲的crimmeni呢? 對了, 就是它了. 原來連佧內豹鼠這麼普通的老鼠中都會混到長吻的種類(還有狐狸吻的種類, 日名為ロングノーズカネイ), 真是太神奇了. 另外今天也在小黑的店看到好久不見非常漂亮的非洲產脂鯉安東尼燈(=阿度尼斯燈)(Lepidarchus adonis)(APT進口), 可惜數量實在是太少了.

魚隻來源: 台族水族, 水世界, 小黑的店, 石頭水族 & APT
圖片連結: www.otsuka-nettaigyo.com (photo credit: 大塚慎太郎), rva

尾巴大遇到敵人閃得快的巴哈馬食蚊魚過得較爽且與慢慢來的同類間發生遺傳分化

文獻來源: Langerhans, R.B. 2009. Morphology, performance, fitness: functional insight into a post-Pleistocene radiation of mosquitofish. Biology Letters 5(4): 488-491.

Abstract
Bahamas mosquitofish (Gambusia hubbsi) colonized blue holes during the past approximately 15 000 years and exhibit relatively larger caudal regions in blue holes that contain piscivorous fish. It is hypothesized that larger caudal regions enhance fast-start escape performance and thus reflect an adaptation for avoiding predation. Here I test this hypothesis using a three-pronged, experimental approach. First, G. hubbsi from blue holes with predators were found to possess both greater fast-start performance and greater survivorship in the presence of predatory fish. Second, using individual-level data to investigate the morphology–performance–fitness pathway, I found that (i) fish with larger caudal regions produced higher fast-start performance and (ii) fish with higher fast-start performance enjoyed greater survivorship in the presence of fish predators—trends consistently observed across both predator regimes. Finally, I found that morphological divergence between predator regimes at least partially reflects genetic differentiation, as differences were retained in fish raised in a common laboratory environment. These results suggest that natural selection favours increased fast-start performance in the presence of piscivorous fish, consequently driving the evolution of larger caudal regions. Combined with previous work, this provides functional insight into body shape divergence and ecological speciation among Bahamian blue holes.

另請參見R. Brian Langerhans的個人研究網頁

圖片連結: www.viviparos.com (photo credit: Miguel Andrade)

坦干依喀湖產坦伯拉鳳凰體型大小的多次獨立演化可作為趨異天擇作用的事證

文獻來源: Takahashi T, Watanabe K, Munehara H, Rüber L, Hori M. 2009. Evidence for divergent natural selection of a Lake Tanganyika cichlid inferred from repeated radiations in body size. Molecular Ecology 18(14): 3110-3119.

Abstract
Divergent natural selection is thought to play a vital role in speciation, but clear, measurable examples from nature are still few. Among the many possible sources of divergent natural selection, predation pressure may be important because predators are ubiquitous in food webs. Here, we show evidence for divergent natural selection in a Lake Tanganyika cichlid, Telmatochromis temporalis, which uses burrows under stones or empty snail shells as shelters. This species contains normal and dwarf morphs at several localities. The normal morph inhabits rocky shorelines, whereas the dwarf morph invariably inhabits shell beds, where empty snail shells densely cover the lake bottom. Genetic evidence suggested that the dwarf morph evolved independently from the normal morph at two areas, and morphological analysis and evaluation of habitat structure revealed that the body sizes of morphs closely matched the available shelter sizes in their habitats. These findings suggest that the two morphs repeatedly evolved through divergent natural selection associated with the strategy for sheltering from predators.

圖片連結: cichlidmadness.com (photo credit: Craig Parmley)

南越產裸趾虎之一新種

文獻來源: Geissler P, Nazarov R, Orlov NL, Bohme W, Trung MP, Truong QN, Ziegler T. 2009. A new species of the Cyrtodactylus irregularis complex (Squamata: Gekkonidae) from southern Vietnam. Zootaxa 2161: 20-32. [摘要下載]

Abstract
We describe a new species of the genus Cyrtodactylus from southern Vietnam, based on voucher specimens collected from Dong Nai and Ba Ria – Vung Tau provinces. Cyrtodactylus cattienensis sp. nov. is distinguished from the remaining Indochinese bent-toed geckos by a combination of the following characters: size small, with a maximum SVL of 69 mm; neck band present, extending to the posterior margin of the eye; trunk, tail and limbs bearing irregularly shaped bands: 4–6 light bands on trunk and 4–12 white bands on tail; 16–22 irregular longitudinal rows of dorsal tubercles; 28–42 longitudinal rows of ventrals at midbody; lateral folds weakly developed or absent, without enlarged tubercles; tail not depressed, not enlarged at base, scales arranged in whorls; males with 6–8 precloacal pores in angular continuous series; a patch of enlarged precloacal scales present in both sexes; 3–8 slightly enlarged femoral scales on each hind limb in both sexes; femoral pores absent; precloacal groove absent; subcaudal scales small, not transversely enlarged.

2009-07-15新進魚隻

Sternopygus sp. cf. aequilabiatus 金帶飛刀 x 4
Corydoras "Black Venezuela"黑鼠 x 6 (阿就仙草蜜樣的可愛鼠啊)

Corydoras bondi 邦迪鼠 x 6 (比想像中狀況ok一點)
Corydoras condiscipulus 康帝斯鼠 x 3
Corydoras acrensis (???) 阿克力鼠 (???) x 6
Corydoras weitzmanni 魏茲曼尼鼠 x 6
Corydoras acutus 黑鰭鼠(貝倫產) x 4 (側線黑帶清楚型)
Corydoras acutus 黑鰭鼠(秘魯產) x 8 (側線黑帶不清楚型)
Corydoras sp. cf. aeneus (S Brazil) 南方咖啡鼠 (=コリドラス　ダークレッドエネウス) x 4
Anableps anableps 四眼魚 x 2
Alestopetersius sp. cf. nigripterus 彩虹剛果燈 x 6
Hyphessobrycon sp. 米諾水晶旗 x 2
Characidae sp. 綠線水晶燈 x 2
Characidae sp. 黑鑚黑霓虹 x 2
Characidae sp. 黑尾綠玻璃燈 x 2
Characidae sp. 霓虹精靈燈 x 2
Characidium sp. 大帆黃金跳鱸 x 3-4

今日重點是那個"阿克力鼠". 我想這次進口的種類應該不是acrensis (見模式標本), 而是比較接近Corydoras julii的一種鼠魚. 鼠魚春秋裏的手繪圖(最上圖)與模式標本有一些小小的出入, 不過應該是原繪圖者所見標本的誤差所致. Scotcat與鯰魚星球上所顯示的魚都比較接近真正的acrensis, 然而I Love Corydoras與Coryforum.de所顯示的圖片則比較接近這次APT進口的魚. 另外一個非常類似的種類是古畢豹鼠C. copei (見上面的模式標本照片), 大家可以參考比較一下.

魚隻來源: 石頭水族 & APT, 華洋水族
圖片來源: Tedsfishroom.com, ACSI Project, 鼠魚春秋 (感謝曾偉杰大大提供圖片)

Biawak 3(2)出刊!

本期內容如下, 全文於此下載

Volume 3 Number 2

• Complete Issue
• Cover and Inset
• Organizational News
• News Notes
• Monitoring the Trade: Using the CITES Databaes to Examine the Global Trade in Live Monitor Lizards (Varanus spp.) ANGELO P. PERNETTA
• Ecological Function of Venom in Varanus, with a Comnpilation of Dietary Records from the Literature KEVIN ARBUCKLE
• A Third Captive Generation of Komodo Dragons (Varanus komodoensis) at Rotterdam Zoo, The Netherlands GERARD VISSER, SANDRA BUHOLD and JUDITH VAN DER KOORE
  
• Cannibalism in Captive Varanus timorensis CSABA GECZY
• Current Research
• Recent Publications

Photo credit: Harri Väyrynen. http://www.flickr.com/photos/harrivayrynen/

2009-07-03新進魚隻

Corydoras condiscipulus 康帝斯鼠 x 2
Corydoras aurofrenatus (=CW005) 銀翅鼠 (=鑽紋長腰鼠) x 4 (不是I Love Corydoras所顯示的個體)(上圖)
Corydoras acutus or C109 黑鰭鼠 x 8 (下圖)

Vandellia sp. cf. beccarii 吸血鯰 x 3
Auchenipterus sp. cf. nigripinnis 黑翅虎鯨 (=黑翅項鰭鯰, 虎頭鯊鮫鯨) x 6
Piabucus dentatus 黑唇螢光暴牙燈 (超大隻的蜻蜓燈樣脂鯉) x 2

今日主題是低調奢華系列, 白話一點說就是"實在看不出來是貴在什麼那裏但真的是不常見".

"Corydoras acutus"這條魚在台灣市場上少有整批輸入的記錄, 最近則分別由APT與台族水族引進, 牠雖然是acutus這個種群的代表物種(因為被發表的年代是最早的), 然而在水族市場上的流通上極少, 而牠的鑑定也還存在著一些問題. 我們目前對Corydoras的親緣關係與分子鑑定工作顯示acutus這個種群, 也就是俗稱的"狐狸吻型老鼠", 如同其它的鼠魚種群一樣, 也可能存在著雜交, 多態性, 以及incomplete lineage sorting的現象 (兩個物種因為分化時間不夠久, 在基因層次上仍然可以偵測到一些交流). 所謂的黑鰭鼠的特徵就是"背鰭上有一個大大的黑斑". 然而這樣的斑紋在其它的鼠魚中也能見到 (例如C42 (=Kristina), C77, C109以及所謂的長吻斑豹鼠), 在水族市場上流通的"acutus"的性狀也相當多樣化 (例如這個秘魯出口商的魚), 這不禁令人懷疑所謂的"acutus"是否只是一群"背鰭帶有大黑斑的"狐狸吻鼠魚的集合? 事實上上週由APT所引進的acutus看起來是比較接近C77這個樣子(因為缺乏尾柄附近側線處的黑線), 而本週由台族引進的"acutus"看起來則比較像是C109. 這些魚倒底是什麼樣的關係? 真正的acutus又應該長什麼樣子(見模式標本)? 真的如Ian Fuller在其書中所說是一個變化多端的種嗎?

銀翅鼠的出現是有些出乎意料之外的, 即始在日本的鼠魚專門店中也並不是常見的種類. Corydoras aurofrenatus倒底是不是一個有效種有長期的爭議. Knaack在2004年發表一篇短文確認了這個種的有效性, 然而日本的網頁卻仍把另一個完全不同的短吻型物種當成aurofrenatus (見I Love Corydoras, Cory-korioyaji.maxs.jp). 比較模式標本的形態就可以知道日本方面的鑑定可能是有疑問的. 由於銀翅鼠產於阿根廷, 因此這條魚很可能就是Ian Fuller所著Identifying Corydoradinae Catfish第357頁所顯示來自阿根廷的種類 (鼠魚春秋一書也有此種照片).

吸血鯰是個難搞的東西. 通常在水族市場上會以Candiru這樣的名稱流通, 可是Candiru其實只是泛指會吸血或吃腐肉或鑽進寄主的南美淡水鯰魚的通稱, 這次進口的種類看起來比較像是Vandellia beccarii而不是V. cirrhosa. (大誤 應該訂正為Plectrochilus) 我不太認為一般人應該在家庭水族箱養這種難照顧的鯰魚. 首先吸血鯰需要頗高的溶氧, 因此製造水流是有必要的; 其次, 牠們對水質的要求頗高, 所以太可怕的水質是可能引起脫膜或急性的細菌性感染; 第三, Vandellia這個屬的吸血鯰只吸大魚鰓部的血, 多大的魚? 也就是可以讓牠們鑽進去的體型(參考這邊的飼養經驗). 牠們大概兩週到三週要吸一次血, 吸完以後就會躺在水底不太活動. 但是在吸完血以後, 馬上要把死亡的大魚撈除且要換水, 否則水質會很快地惡化. 這麼難搞的東西其實真的不太適合一般人養, 而且最好不要為了炫耀給朋友看養這東西表演餵食秀.

至於首次輸入的Auchenipterus nigripinnis是一種活潑的頸鰭鯰(項鰭鯰). 這個科的魚類有幾種活動方式: (1) 一整隻肥肥懶惰睡覺型 - 如黑魔鯨, 麻花魔鯨, 綠魔鯨; (2) 愛睡覺但有吃的就開心地游來游去型 - 木頭貓, 釣魚貓, 小豹鯨(之類的); (3) 害羞慢游型 - 如黃金龍貓豹鯨, 枯葉虎鯨, 二線虎鯨, 紫虎鯨; 還有(4)隨時隨地開心地游來游去型 - 雙黑尾小虎鯨, 還有今天抓到的Auchenipterus nuchalis. 這個種對人工飼料的接受度很高, 尤其是浮水型的小顆飼料, 雖然說紅蟲也不錯, 但是這類的魚對已經沉底的餌料的搜尋能力沒有底棲性種類來得好, 因此浮水或可懸浮的飼料應該是比較適當的選擇. 有關這個種的圖片可以參考德國Glaser, 日本Aqua Shop與Aqua Shop True的圖片. 順道一提, 一定有人覺得這玩意兒不就是小隻的虎頭鯊嗎? 有些學者在過去的確認為亞洲的巨鯰科(Pangasiidae)與南美產的頸鰭鯰科是比較接近的類群, 不過近年的研究都指出頸鰭鯰其實比較接近囊鯰(也就是哭貓笑貓愛爾溫尼...), 所以說這麼類似的體型只是趨同或平行演化的產物.

魚隻來源: 台族水族, 水世界, 石頭水族 & APT
圖片連結: Coryforum.de (photo credit: Ingo Seidel), 鯰魚星球 (photo credit: Sergio Ledo), JJPhoto.dk

A preliminary phylogeny of Corydoradinae - continued

繼四月份的初步結果後, 最近又得到新的結果, 使用超過450隻鼠魚樣本, 目前發現一些有趣的事, 首先是鼠魚的天然種間雜交可能非常盛行, 尤其是哥倫比亞產的短吻種類幾乎都有雜交現象, 也就是說, 有一些C-numebrs, 不管數量多不多, 都可能起源自複雜的雜交事件. 所謂的花紋變化多端的金花豹鼠(C. leopardus)也可能是一群雜交鼠的集合. 長吻雙色鼠與一間鼠應該如Ian Fuller所推測是同一種, 而柯瑞塔鼠, 佛列律鼠與黑影鼠則是同一種的不同色型. 有一些類群的關係是符合預測的, 例如奧波根鼠的姐妹種是potaroensis, tukano的姐妹種是reynoldsi, 然而所謂的紅頭系列卻沒有一個種是彼此最近緣的親戚. 此外Aspidoras不是一個單系群, 然後Brochis, Scleromystax與Corydoras各種群仍然混在一起. 傳統的種群分類目前看起來只有aeanus group與paleatus group是單系群, 其它都不是.

2009-07-02新進魚隻

Corydoras sp. 金線差差鼠 x 3
Corydoras sp. hybrid (caudimaculatus x ?) x 3
Corydoras sp. hybrid (疑似leucomelas x trilineatus) x 1
Corydoras "Deckeri" (=C03) x 1
Loricaria parnahybae or similima 西屯路產陰陽直昇機 x 3

嗯, 現在的問題是, Deckeri真的是一個有效的物種嗎? 或只是英哥鼠axelrodi的一型呢?

魚隻來源: 旭海水族, 雅麗水族, 靚魚坊, 海洋水族
圖片連結: Let's Enjoy Corydoras

琵琶鼠上下顎機動性促使其有效刮取食物

文獻來源: Adriaens D, Geerinckx T, Vlassenbroeck J, Van Hoorebeke L. 2009. Extensive Jaw Mobility in Suckermouth Armored Catfishes (Loricariidae): A Morphological and Kinematic Analysis of Substrate Scraping Mode of Feeding. Physiological and Biochemical Zoology 82(1):51–62. 2009. DOI: 10.1086/594378

Abstract
Loricariidae, or suckermouth armored catfishes, possess upper and lower jaws that are ventrally oriented and that bear teeth that touch the substrate from which algae and other food items are scraped. The ventral orientation and the highly specialized morphology of the jaws, characterized by protrusible upper jaws and left‐right decoupled lower jaws, are observed in Pterygoplichthys disjunctivus, the species investigated here. Kinematic data of the scraping feeding movements, obtained by external high‐speed and x‐ray recordings, are used to quantify jaw movement, especially to test for upper jaw mobility and versatility during substrate scraping. Our results show that the mobility of the jaws is indeed high compared with what is standard for catfishes. The upper jaw's ability to perform a substantial degree of rostrocaudal movement is quite unique for catfishes. The ventromedially oriented lower jaws, with the teeth and the coronoid process at opposite sides, display an extensive mobility: they rotate around the suspensorial articulation and around their longitudinal axis, resulting in an extended scraping movement and thereby covering a large surface area. The lower jaws also show a left‐right asymmetry in their movements during scraping. Thus, our results suggest that the extreme morphological specializations of the jaws in loricariid catfishes are linked to an increased mobility and functional versatility, allowing these animals to efficiently scrape algae from substrates with irregular surfaces.

延伸閱讀: 鯰魚如何從吸食, 舔食變成刮食?

圖片連結: planetcatfish

半水棲的紅樹巨蜥不在乾季時顯著降低體溫與代謝率

文獻來源: Smith JG, Christian K, Green B. 2008. Physiological Ecology of the Mangrove‐Dwelling Varanid Varanus indicus. Physiological and Biochemical Zoology 81(5):561–569. 2008. DOI: 10.1086/590372

Abstract
Some species of terrestrial lizards in wet‐dry tropical climates reduce their body temperatures (Tb's) and activity and lower their metabolic rates during the dry season when food and water resources are scarce. However, semiaquatic lizards have access to water and presumably food throughout the year, so it is possible that they will not have the seasonal response seen in terrestrial species. We studied the thermal biology, energetics, and water flux of Varanus indicus, a semiaquatic, mangrove‐dwelling varanid in tropical northern Australia. Although V. indicus remained active all year, they reduced their activity in the dry season, but not to the extent of terrestrial varanids. Varanus indicus field metabolic rates decreased by 38% in the dry season mostly as a result of the reduction in activity. Although food and water depletion are the driving forces behind decreases in dry season Tb selection and energetics for many varanids, V. indicus appears not to be subject to these pressures to the same extent. Thermoregulatory indices indicate that V. indicus actively thermoregulate in the wet and dry seasons, but they do not fully exploit the available thermal resources. These lizards are unusual among varanid lizards in that their midday Tb's are relatively low (about 31°C) despite the availability of thermal resources that would allow them to attain substantially higher Tb's.

圖片連結: varanus.nl

散熱品質對鬆獅蜥的溫度調節行為之效應

文獻來源: Cadena V, Tattersall GJ. 2009. The Effect of Thermal Quality on the Thermoregulatory Behavior of the Bearded Dragon Pogona vitticeps: Influences of Methodological Assessment. Physiological and Biochemical Zoology 82(3):203–217. 2009. DOI: 10.1086/597483.

Abstract
Metabolic functions are generally optimized within a narrow range of body temperatures (Tb's), conferring thermoregulation great importance to the survival and fitness of an animal. In lizards, Tb regulation is mainly behavioral, and the metabolic costs associated with behavioral thermoregulation are primarily locomotory. In reptiles, however, it has been proposed that they thermoregulate less precisely when the associated costs, metabolic or otherwise, are high. Such a strategy enhances fitness by allowing lizards to be more flexible to changing environmental conditions while maximizing the benefits of maintaining a high Tb and minimizing energy expenditure. We evaluated the behavioral thermoregulation of inland bearded dragons Pogona vitticeps under various thermal quality conditions requiring different locomotory investment for thermoregulation. The selected ambient temperature and preferred Tb ranges increased at lower environmental thermal qualities, indicating a decrease in thermoregulatory precision in environments where the costs associated with thermoregulation were high. The level of thermoregulation was also affected, exhibiting a decrease in preferred Tb of 2°C at the lowest‐thermal‐quality treatment. These data provide important implications for the procedural assessment of preferred Tb and a better understanding of thermal set points in reptiles in general. Our results emphasize that the precise maintenance and assessment of preferred Tb is contingent on the quality of the environment, laboratory or natural, that the animal inhabits.

圖片連結: davidwallphoto.com

皮質酮對兩種由環境溫度決定子代性別蜥蜴的子代發育與性比具有完全相反的效應

文獻來源:Warner DA, Radder RS, Shine R. 2009. Corticosterone Exposure during Embryonic Development Affects Offspring Growth and Sex Ratios in Opposing Directions in Two Lizard Species with Environmental Sex Determination. Physiological and Biochemical Zoology 82(4):363–371. [網址]

Abstract

Stress experienced by a reproducing female can substantially affect the morphology, behavior, and physiology (and hence fitness) of her offspring. In addition, recent studies demonstrate that stress hormones (corticosterone) influence sex determination of embryos. To explore these issues, we manipulated corticosterone levels in eggs of two Australian lizard species (Amphibolurus muricatus and Bassiana duperreyi) that exhibit temperature‐dependent sex determination (TSD). Elevated corticosterone levels during embryonic development affected body size, growth rates, and sex ratios of the resultant offspring, but the direction and magnitude of these effects differed between the species. Corticosterone enhanced growth rates of hatchling B. duperreyi but inhibited growth of A. muricatus. Eggs with elevated levels of corticosterone produced more daughters in A. muricatus and more sons in B. duperreyi. The sex‐ratio effect in A. muricatus may have been due to sex‐specific embryonic mortality, but it may represent a direct effect on sex determination in B. duperreyi (because embryonic mortality was not affected by corticosterone manipulation in this species). These results demonstrate the complexity of proximate mechanisms for sex determination among reptiles with TSD and illustrate the potential role of corticosterone in sex‐determining systems.

延伸閱讀: 錯綜複雜的蜥蜴性別決定, 雄澳大利亞水手蜥用俯臥撐來嚇跑對手

圖片連結: The Nature of Tasmania, The EarthSky.org (photo credit: Benjamint444)